Theory of Itinerant Electron Magnetism , Jürgen Kübler Oxford U. Press, New York, 2000. $120.00 (427 pp.). ISBN 0-19-850028-9
An incredible variety of insulators, conductors, and superconductors are known to present magnetic behavior, making magnetism one of the most important subfïelds of condensed matter physics. The importance of magnetism is also amplified by a plethora of technological applications. Magnetic materials find their place in our daily lives as permanent magnets in motors, transformers, storage media in computers, cassette tapes, switches, and many other devices.
In the past 15 years, the field of magnetism has exploded with exciting new discoveries. These include new magnetic semiconductors, new magnetic superconductors, the colossal magnetoresistance (CMR) effect in manganese oxides, and the giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR) effects in magnetic multilayers at the nanometer scale. Moreover, magnetic materials play a vital role in the new field of spintronics and may well play an important role in quantum computers—if such devices are ever built.
Theory of Itinerant Electron Magnetism by Jürgen Kübler is a unique contribution to the study of magnetism, in that it attempts to describe a substantial part of the field using the local density functional approximation (LDA). The author concentrates on itinerant electron systems and emphasizes the importance of the electronic structure to the understanding of magnetic properties of realistic materials. Furthermore, Kübler cautions the reader that LDA does not correspond to the independent-particle picture; he advocates the extensive use of computers to solve the many-electron problem within LDA. However, he makes it very clear that LDA programs running on even the most efficient computers are not the answer to all magnetism questions, particularly those dealing with strongly correlated electron systems, for which no controlled general theory truly exists.
Kübler does an excellent job of describing LDA and making connections between the electronic structure of several materials and their magnetic properties. Nonetheless his book is not and was not meant to be a treatise on all aspects of magnetism. It has its place among many books on the subject. The intended audience for Theory of Itinerant Electron Magnetism is graduate students and researchers engaged in research in basic and applied magnetism. The book will be useful to many researchers, theorists, and experimentalists alike. It seems too long, however, for an advanced graduate textbook on the theory of magnetism.
Parts of the book are probably well suited for a special-topic graduate class in magnetism, but students may have to read first (or concurrently) more broad-based discussions of magnetism. In particular, Theory of Magnetism, by Key Yosida (Springer-Verlag, 1996) includes discussions not only of itinerant magnetic systems but also of magnetism in localized spin systems and in dilute alloys. In addition, the shorter monographs, Spin Fluctuations in Itinerant Electron Magnetism, by Toru Moriya (Springer-Verlag, 1985), and Quantum Theory of Magnetism, by Robert M. White (Springer-Verlag, 1970, 1983) can provide some alternative views of the state of the field—at least up to the early 1980s.
Theory of Itinerant Electron Magnetism contains very clear presentations of some important aspects of magnetism of the 1990s. Discussions of half-metallic ferromagnets and of the GMR effect in magnetic multilayers are very illuminating. More recent developments, such as TMR, CMR, and magnetic quantum phase transitions, are not included. However, as these new areas of research unfold, readers might expect these topics to appear in later editions.
In summary, Theory of Itinerant Electron Magnetism by Jürgen Kübler is a very good book for researchers engaged in basic and applied magnetism. It offers a personal and focused view of itinerant magnetism based on LDA from a leading expert in the field, and it describes in detail the relationship between electronic structure and magnetic properties of itinerant electrons in realistic systems.
